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How might the Beachy Head area have looked 90 million years ago?

Introduction

Beachy Head is an area of spectacular coastline and countryside
located on the most southerly tip of East Sussex, 1.5 miles southwest of Eastbourne.
The area is well known for its chalk cliffs that tower above
the characteristic Beachy Head lighthouse with its red and white
striped paintwork. The cliffs between Eastbourne and Beachy Head are part of a
sequence of cliffs that extend a further 4.5 miles to Cuckmere Haven
in the northwest, and encompass the famous undulating contour of
Seven Sisters.

Left: View west at
Beachy Head during low-tide; the lighthouse is dwarfed by the towering
chalk cliffs. Right: Beachy Head lighthouse.

The rocks and clays at Beachy Head span 17 million years of deposition between
103-86 million years ago (mya), and record the transition from shallow,
near-shore conditions to deeper water and the earliest associated
chalks. Fossils occur commonly throughout the chalk, in particular
echinoids, sponges, bivalves, and other benthic fauna that inhabited the
prehistoric seafloor at the time.

Left: Two children
admire an ammonite Mantelliceras discovered on a loose
boulder. Right: A bivalve valve 'Pecten' with the counterpart
impression.

The best place to access Beachy Head is from Eastbourne, via King
Edward's Parade which runs along the seafront. At the western end of the
seafront the road bends to the right and continues up the hill, at which
point parking is available outside a small cafe.

Left: Parking is
available at the end of the coast road. Right:
A path runs between the school and the cafe, and leads to the beach
access point at Cow Gap.

From the parking area a public footpath runs alongside the cafe, past an
iron gate (shown above) and towards the cliff-top. The path follows the
coastline approximately 1.5 miles to Cow Gap, at which point a flight of
wooden steps extend to the beach.

Left: Following the
hill-top along the coast, signposts direct the way to Cow Gap.
Right: Wooden steps at Cow Gap provide access to the beach.

The geology of Beachy Head

The rocks and clays at Beachy Head record a
fascinating history dating from the Late Cretaceous epoch, c.103 to c.86
mya, and provide evidence of dramatic geological changes that took place
during this time. Among the events recorded is the transition from a
shallow near-shore environment, during which sands and clays were
deposited, to higher sea levels and the first associated grey and white
chalks. At this time Beachy Head and much of Great Britain, along with
Europe, lay around 40°N of the equator, on an equivalent latitude to the
Mediterranean Sea today.

Figure 1: View from Cow Gap overlooking the earliest deposits exposed
and the transition to the Chalk at the cliff base. *Limited in situ
material, mostly boulders.

The earliest deposits at Beachy Head belong to the Upper Gault, a dark
grey, sticky (when wet) clay dating from the Upper Albian stage,
approximately 103 mya (see fig.1 above and photo below-left). The
Gault clay is understood to have formed relatively close to land (compared to
chalk), but at sufficient distance and depth that the
seabed was undisturbed by wave energy and strong tidal currents, that
might otherwise have introduced a greater volume of sand to the
sediment. Only fine silts could be carried this far from land. The
abundance of delicate, thin-shelled benthonic fauna (creatures living of
the seafloor) is further evidence of relatively calm, undisturbed
conditions.

Left:
The Gault clay on the foreshore at Cow Gap is the earliest deposit
at Beachy Head. Right: The overlying Upper Greensand
visible in situ in the foreground.

Resting above the Gault clay but below the overlying Chalk is the
Upper Greensand (above-right), a course sandy sediment which probably reflects a
minor regressive phase, during which the lower sea level reduced the
distance from land and allowed sand to be reintroduced
to the area.

Overlying the Upper Greensand is the Chalk including the Glauconitic
Marls at its base.
Figure 2 below-left shows the transition from Upper Greensand
(visible on the foreshore) to the overlying Chalk (visible in the
cliff). As sea levels rose, pushing the coastline
further away, the volume of land sourced sediment that contributed
to the Upper Greensand gradually reduced,
leaving one main source for continued sedimentation - marine
plankton.

The Chalk is largely comprised of the skeletal remains of
planktonic algae known as coccolithophores which accumulated to form
a white ooze on the seafloor. This soft sediment was later compacted
and hardened (lithified) to form chalk - a relatively soft rock
itself. The evidence of higher sea levels is reflected in the
progressively white chalk seen higher in the cliffs. The purity of
the chalk indicates its formation took place far from land, free of
terrestrial sands and silts that would otherwise have coloured it.

In comparison with present-day conditions, global sea-levels during
the Late Cretaceous were over 200 meters higher. The higher sea levels
likely reflect a combination of extreme greenhouse conditions and
heightened plate tectonics. Elevated plate tectonic activity and the
associated volcanics delivered greenhouse gases to the atmosphere,
fuelling the greenhouse effect. Global high temperatures melted much
(perhaps all) of the ice at high latitudes, introducing significant
amounts of water to the world's oceans. Uplift of the ocean-floor in
regions of active plate tectonics displaced further water onto the
continental shelves.

Today the chalk appears above sea level, the
result of lower present-day sea levels and widespread uplifting caused by the pressure of the European
and African continental plates colliding (generating the Alps), a process that took place at
its greatest extent 30-25 mya. More recently, following the end of the
last ice age and subsequent increase in sea levels (albeit to a less
extent than 84 million years ago), the coastline has moved inland,
exposing the elevated chalk to intensive erosion and sculpting it into a
vertical cliff-face.

Figure 3 and 4 below provide a summary of the geological horizons present in the
cliffs and on the foreshore east of Cow Gap. The first is taken from
the end of Head Ledge looking back towards the cliffs and
lighthouse, and the second is taken from the base of the lighthouse.
Beachy Head is one of only a small number of UK locations where the Lower, Middle
and Upper Chalk is exposed.

Figure 3: Summary of the key geological horizons
visible from Head Ledge towards Beachy Head lighthouse to the west
and Eastbourne to the northeast.

Figure 4: Summary of the key geological horizons seen
from Beachy Head lighthouse towards the Belle Tout lighthouse in the
west and Head Ledge in the east.

One of the key markers visible in the cliff-face is the Seven Sisters Flint Band, a
conspicuous dark-coloured sheet flint visible within the Seaford Chalk
at the cliff-top opposite Beachy Head lighthouse (indicated as a red
line in figures 3 and 4 above). Travelling west, beyond the Belle Tout
lighthouse, the Seven Sisters Flint Band reaches beach
level (shown below-left).

Left: Seven Sisters
Flint Band at beach level, west of Beachy Head. Right: Seven Sisters Flint
Band (SSFB) high in the cliffs opposite Beachy Head lighthouse.

Although flint is inorganic, the silica that formed it was originally
sourced from the remains of sea sponges and siliceous planktonic
micro-organisms (diatoms, radiolarians). Flints are concretions that
grew within the sediment after its deposition
by the precipitation of silica; filling burrows/cavities and
enveloping the remains of marine creatures, before dehydrating and
hardening into the microscopic quartz crystals which constitute
flint. To discover more about flint
click here.

Another point of interest are the Plenus Marls, a band of
darker-grey chalk (c.8m thick) located in the uppermost portion of
the Zig Zag Chalk Formation. From Hedge Ledge the gradual dip of the
chalk brings the Plenus Marls to beach level a short distance east
of the lighthouse (fig.5 below-left).

Figure 5: Plenus Marls
(named after the belemnite Actinoclamax plenus found within
them) exposed on the foreshore and in the cliff east of the lighthouse.
Right: A belemnite guard Actinoclamaxin situ
within the Plenus Marls.

At low-tide the Plenus Marls are well exposed on the foreshore,
providing an opportunity to search for the comparatively rare belemnite guards belonging to Actinoclamax (above-right).
The guards can sometimes be found exposed on the surface of the eroding beach
platform; their dark-amber colouration and semi-translucent
character makes them easily distinguishable from the surrounding
chalk matrix.

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Where to look for fossils?

Fossils can be found on the foreshore and at the base of the cliffs
in either direction from Cow Gap. The most productive (and safest) place
to search for fossils is on the foreshore at low-tide. Chalk boulders
and flint nodules are scattered along the entire section, providing a
constant supply of fossils.

Left: Lucinda searches
for fossils among the flint pebbles on the foreshore. Right:
Robert shows an event participant an ammonite within a loose boulder.

For first time visitors and families in particular, the stretch of
low-gradient cliff immediately southwest of the steps at Cow Gap provides a relatively
safe and productive location to search for fossils. The chalk here
belongs to the West Melbury Marly Chalk Formation and is rich in
ammonites and bivalves in particular (below-left).

Please note the beach platform and cliffs are assigned
SSSI status, which requires visitors avoid damaging (including
hammering) the area. From a fossil collecting perspective this means
it's not permitted to extract specimens that are in situ. Collecting
efforts should be directed towards the loose boulders and pebbles on the
foreshore.

As with all coastal locations, a fossil hunting trip is best timed to coincide
with a falling or low-tide. For a relatively low one-off cost we
recommend the use of Neptune Tides software, which provides
future tidal information around the UK. To download a free trial
click here.

What fossils might you find?

The fossils at Beachy Head are diverse, reflecting a dynamic and
changing prehistoric marine environment. Many of the fossil groups
are common throughout the various horizons, in particular ammonites,
bivalves and sponges. Although ammonites are well documented from
the Gault clay and overlying Greensand they are not commonly found
and it may take several visits before a specimen is located. We
welcome photos of any ammonites in situ within the Gault or
Greensand at Beachy Head (contact
us).

The rocks exposed at Beachy Head are dominated by the Chalk and
associated flints, and it's from these respective deposits and
concretions that the greatest volume and diversity of fossils can be
found. Among the common finds are echinoids, brachiopods,
gastropods and bryozoans; less common finds include shark teeth,
nautili and crustacean burrows lined with fish scales; on rare
occasions belemnites, articulated lobster and fish skeletons, and
plant remains can also be found.

Below are a selection of finds made over many visits to Beachy
Head. Where possible the specimen's genus has been indicated below
each photo, if a confident ID can't be achieved a question mark has
been added to indicate so.

Left: A worn ammonite, encrusted with oyster shells,
in situ within the Zig Zag Chalk Formation. The presence of
oysters provides evidence
that the ammonite's
shell lay exposed on the seabed for a sufficient time for encrusters to colonise its surface.
It's less common to find such a large number in a single
association.Right: A close-up reveals the oysters have
colonised most of the ammonite's ribbed shell.

Left: A unidentified ammonite fragment, found
loose on the beach, originally derived from the Upper Gault Clay
Formation.
Right: A Eutrephoceras(?) nautilus found
within a loose boulder on the foreshore.

Left: A Actinoclamax belemnite guard in situ on the foreshore within the Plenus Marls, Zig Zag Chalk.
Right: A Palaeastacus lobster claw, found within a fallen
Lower Chalk boulder. Reducing the matrix will reveal how much of the
specimen is concealed.

Left: A
lobster burrow in situ within the Gault clay on the foreshore.
Right: A Bathrotomaria gastropod found in loose rocks east of Cow Gap.

Left: Jonathan with a gastropod impression, Lower Chalk.
Right: A spiny Spondylus bivalve found on the surface of a fallen boulder, Upper
Chalk.

Left: A single
'Pecten' bivalve valve in situ on the foreshore, West Melbury Marly Chalk. Right: A Concinnithyris brachiopod,
Zig Zag Chalk.

Left: A flint pebble
containing fragments of an inoceramid bivalve shell.
Right: An inoceramid bivalve shell on the surface of an
air-weathered boulder.

Left: A
Cretalamna(?) shark tooth, found within a loose boulder at the cliff base.
Right: A Ptychodus shark tooth, found on the surface of a
fallen boulder.

Left: An articulated
Beryx fish skeleton, with the top of the skull in
cross-section and the vertebrae exposed behind it. Found on a loose
boulder, Lower Chalk.
Right: A Terebella crustacean burrow lined with fish scales.
These fossils
are sometimes mistaken for articulated fish remains.

Left: An Echinocorys
irregular echinoid
encrusted with oysters.
Right: The internal flint mould of an Echinocorys echinoid protruding from
the cliff base.

Left: A
Micraster
echinoid
on the surface on an air-weathered boulder. Right:
The internal flint mould on a Micraster echinoid.

Left: A fragment of
Tylocidaris echinoid shell. Right: A Tylocidaris echinoid spine exposed on the surface of an air-weathered
boulder.

Left: An
undetermined polyzoa (20mm) on the surface of an air-weathered boulder.
Right: A bryozoan (10mm).

Left: A worm tube (40mm) exposed on the surface of a large fallen boulder.
Right: A solitary Micrabacia coral (8mm).

Left: A sponge on the
surface of a piece of chalk.
Right: A Exanthesis sponge, Glauconitic Marl Member
/ West Melbury Marly Chalk Formation.

Left: A split flint
pebble containing a sponge in cross-section. Right:
Charlotte with a second sponge in cross-section within a flint pebble.

Tools & equipment

Left: A well
equipped family fossil hunting at Beachy Head. Right:
A strong rucksack and walking boots are recommended.

It's a good idea to spend some time considering the tools and
equipment you're likely to require while fossil hunting at Beachy
Head. Preparation in advance will help ensure your visit is
productive and safe. Below are some of the items you should consider
carrying with you. You can purchase a selection of geological tools
and equipment online from
UKGE.

Hammer:
A strong hammer will be required to split prospective rocks. The
hammer should be as heavy as can be easily managed without causing
strain to the user. For individuals with less physical strength and
children (in particular) we recommend a head weight no more than
500g.

Chisel: A chisel is required in conjunction with a
hammer for removing fossils from the chalk. In most instances a
large chisel should be used for completing the bulk of the work,
while a smaller, more precise chisel should be used for finer work.
A chisel founded from cold steel is recommended as this metal is
especially engineered for hard materials.

Safety glasses: While
hammering rocks there's a risk of injury from rock splinters
unless the necessary eye protection is worn. Safety glasses ensure any splinters are deflected away from the eyes. Eye
protection should also be worn by spectators as splinters can
travel several metres from their origin.

Strong bag: When considering the type of bag to use it's worth setting aside
one that will only be used for fossil hunting, rocks are usually
dusty or muddy and will
make a mess of anything they come in contact with. The bag will also
need to carry a range of accessories which need to
be easily accessible. Among the features recommended include: brightly coloured,
a strong holder construction, back
support, strong straps, plenty of easily accessible pockets and a rain cover.

Walking boots: A good pair of walking boots will
protect you from ankle sprains, provide more grip on
slippery surfaces and keep you dry in wet conditions. During your
fossil hunt you're likely to encounter a variety of terrains so
footwear needs to be designed for a range of conditions.

For more information and examples of tools and equipment
recommended for fossil hunting
click here
or shop online at
UKGE.

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FOSSILS

Protecting your finds

It's important to spend some time considering the best way to
protect your finds onsite, in transit, on display and in storage.
Prior to your visit, consider the equipment and accessories you're
likely to need, as these will differ depending on the type of rock,
terrain and prevailing weather conditions.

When you discover a fossil, examine the surrounding matrix (rock)
and consider how best to remove the specimen without breaking it;
patience and consideration are key. The aim of extraction is to
remove the specimen with some of the matrix attached, as this will
provide added protection during transit and future handling;
sometimes breaks are unavoidable, but with care you should be able
to extract most specimens intact. In the event of breakage,
carefully gather all the pieces together, as in most cases repairs
can be made at a later time.

Picture credits: Sponge by 'andrew104' at www.flickr.com;
echinoid by 'topofbroadway' at www.flickr.com; lobster by David Galvan at
www.flickr.com; shark by
'pugwash00' at www.flickr.com.

Safety notice: Fossil hunting can at times pose a risk to personal safety, in particular within environments close to the coast, cliffs
or in quarries and when using the tools and equipment illustrated. Discovering Fossils provides a free resource to inform you about
this fascinating subject and does not accept any liability for decisions made using this information. We recommend all individuals
abide by the fossil hunting guidelines available by clicking on the icon at the top of the page.